CRYSTAL QUEST Whole House Multi/Nitrate 1.5 Water Filter System (Stainless Steel) features 6 stages of filtration. in the first stage, water flows through a 20-inch sediment filter cartridge that removes sediment, silt, sand dirt which also extends the life of water softeners and water filters and prevents damage to control valves or pumps. in the second, third and fourth stages, water flows through a KDF-85, KDF-55 and GAC mineral tank which removes hundreds of contaminants. in the fifth stage, water flows through a nitrate-reducing mineral tank. Finally, in the sixth stage, the water flows through a 20-inch solid carbon cartridge so that it can remove volatile organic carbon compounds (VOCs, insecticides, pesticides and industrial solvents). CRYSTAL QUEST Whole House Multi/Nitrate 1.5 Water Filter System also features: Solid 316-Stainless Steel Tanks filled with REDOX and GAC, a Poly Glass mineral tank filled with a nitrate reducing media, Riser style 1-inch internal flow distributor, a solid state microprocessor with LED display Electronics control valve, Chrome sleeve/jacket, Polyester fiberglass tank and a Stainless Steel Bypass Valve.